diff -r bf3695fee719 -r 481802342fdf ucx/ucx/ucx.h
--- a/ucx/ucx/ucx.h	Mon Feb 04 14:11:57 2019 +0100
+++ b/ucx/ucx/ucx.h	Mon Feb 04 17:17:48 2019 +0100
@@ -37,7 +37,7 @@
 #define	UCX_H
 
 /** Major UCX version as integer constant. */
-#define UCX_VERSION_MAJOR   1
+#define UCX_VERSION_MAJOR   2
 
 /** Minor UCX version as integer constant. */
 #define UCX_VERSION_MINOR   0
@@ -131,6 +131,62 @@
  */
 typedef size_t(*read_func)(void*, size_t, size_t, void*);
 
+
+
+#if __GNUC__ >= 5 || defined(__clang__)
+#define UCX_MUL_BUILTIN
+
+#if __WORDSIZE == 32
+/**
+ * Alias for <code>__builtin_umul_overflow</code>.
+ * 
+ * Performs a multiplication of size_t values and checks for overflow.
+ * 
+ * @param a first operand
+ * @param b second operand
+ * @param result a pointer to a size_t, where the result should
+ * be stored
+ * @return zero, if no overflow occurred and the result is correct, non-zero
+ * otherwise
+ */
+#define ucx_szmul(a, b, result) __builtin_umul_overflow(a, b, result)
+#else /* __WORDSIZE != 32 */
+/**
+ * Alias for <code>__builtin_umull_overflow</code>.
+ * 
+ * Performs a multiplication of size_t values and checks for overflow.
+ * 
+ * @param a first operand
+ * @param b second operand
+ * @param result a pointer to a size_t, where the result should
+ * be stored
+ * @return zero, if no overflow occurred and the result is correct, non-zero
+ * otherwise
+ */
+#define ucx_szmul(a, b, result) __builtin_umull_overflow(a, b, result)
+#endif /* __WORDSIZE */
+
+#else /* no GNUC or clang bultin */
+
+/**
+ * Performs a multiplication of size_t values and checks for overflow.
+ * 
+ * This is a custom implementation in case there is no compiler builtin
+ * available.
+ * 
+ * @param a first operand
+ * @param b second operand
+ * @param result a pointer to a size_t, where the result should
+ * be stored
+ * @return zero, if no overflow occurred and the result is correct, non-zero
+ * otherwise
+ */
+#define ucx_szmul(a, b, result) ucx_szmul_impl(a, b, result)
+
+int ucx_szmul_impl(size_t a, size_t b, size_t *result);
+
+#endif
+
 #ifdef	__cplusplus
 }
 #endif